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40 Orionid Meteors - 23rd October 2011

18

Jan

40 Orionid Meteors - 23rd October 2011

Submitted by Phil

Last weekend at the Lake Eppalock retreat in central Victoria, I tried to repeat the process that got me this previous image of the Geminid meteors in 2009. However since the Orionids are generally a less active shower, I wasn't expecting to be able to do as well. It seems I was wrong.

click for larger image

I doubled up on gear this time and had two Canon 5DmkII cameras running side by side on an equatorial mount to create this mosaic with a pair of 24mm f1.4 lenses wide open. For the sky background, I took a single 4 minute exposure at f2.8 and ISO800 (RAW) for each half of the mosaic. Then from 2:30am to 4:30am local Australian Eastern Daylight Time (22nd Oct 15301730 UT) I kept both cameras running continuously tracking the sky on the Vixen GPDX mount with 4 second exposures at ISO6400 (JPG) generating around 2500 images on each camera.

At home i manually blinked through the full sequence of 5000 frames and selected all of the ones I could find with meteors in them. I used RegiStar to register the meteor frames to the mosaic background created in Photoshop and then masked out the meteors from the sub-frames and added them over the top of the background image. The result is what you see above. The second image below includes all the sporadic meteors that were captured in the same time-frame as well as a few extra Orionids caught deep in twilight at the end of the sequence which look a bit oddly coloured due to the bright blue twilight sky.

All up i count 40 Orionid meteors in the first image above although one is overlapped by another. The image below includes another 4 captured during bright twilight as well as 16 sporadic meteors. Another two Orionids were captured on camera but unfortunately had to be cropped out when trimming the mosaic.

click for larger image

Several of the meteors got clipped by the relatively short exposures and/or appeared in more than one exposure. In one case the meteor train persisted through at least seven frames (30 seconds total). What I found even more interesting was the difference in colour between the meteor itself and the train in the subsequent exposure. The example below is one of the best, with the bright white of the meteor with red fringes, which may be partly a lens artefact, followed by a vivid green train in the subsequent exposure. Nice!

By popular demand, here is an example of what one of the meteors look like in the original 4 second frame at ISO6400. This is from the top right of the first image. It's a small crop but otherwise no adjustment of the jpg image.

Manually finding the meteors out of the 5000 frames is tedious enough but masking them out to overlay on the background image is even more so. I'd love to find a way to make this process easier and faster before i try this again.